Easy-to-open lids generally have a peripheral score, as in the case of containers for food products. Some lids also include a pull tab for tearing an opening in the container, through which the contents of the container can be accessed.
It is often desirable to seal liquids into containers while they are hot, or alternatively, to sterilize liquids by heating them in a sealed container. As the product cools, the containers and lids must have sufficient strength or deformation properties to enable the containers to accommodate the change in internal pressure, i.e. retort. Currently, retortable foil membrane double seam lids are used on vessels containing non-liquid high viscosity products. Some of these foil membrane lids also include a pull tab to facilitate the opening process.
Problems arise when these lids are used on vessels containing low viscosity products. For example, during the retort process, the initial expansion and subsequent contraction of the foil membrane lid could potentially leave the tab extended or otherwise exposed after a heated product has cooled. When this happens, there is a chance that the package can be opened during in-plant distribution—especially when the vessel is conveyed upside down. Moreover, when the lids are used to seal vacuum packed liquids, the pressure differential can cause a splashing effect when the package is opened.
Accordingly, there is a need for an improved retortable foil membrane double seam lid that can be easily opened while reducing the shortcomings set forth above.